Reviving a talking point from his 2016 campaign, President Donald Trump Wednesday called for swift and immediate action against convicted cop killers, saying the death penalty should be in play.

“Dangerous criminals should be punished to the fullest extent of the law,” Trump said. “That’s the only language they understand.”

Trump’s comments came during a speech at the National Peace Officers’ Memorial Day service on Capitol Hill. While speaking to an audience of law enforcement officers from around the country, Trump said cop killings need to come to an end and those who commit those crimes should be dealt with quickly.

“The ambushes and attacks on our police must end, and they must end right now,” Trump said. “We believe that criminals who murder police officers should immediately, but with trial, get the death penalty.”

During the 2016 campaign, Trump said he would sign an executive order calling for the death penalty of anyone convicted of killing a cop. However, he has yet to introduce any official order or proposal that would include language calling for the death penalty in those cases.